Spectral variation of fluorescence lifetime near single metal nanoparticles

Abstract We explore the spectral dependence of fluorescence enhancement and the associated lifetime modification of fluorescent molecules coupled to single metal nanoparticles. Fluorescence lifetime imaging microscopy and single-particle dark-field spectroscopy are combined to correlate the dependence of fluorescence lifetime reduction on the spectral overlap between the fluorescence emission and the localised surface plasmon (LSP) spectra of individual gold nanoparticles. A maximum lifetime reduction is observed when the fluorescence and LSP resonances coincide, with good agreement provided by numerical simulations. The explicit comparison between experiment and simulation, that we obtain, offers an insight into the spectral engineering of LSP mediated fluorescence and may lead to optimized application in sensing and biomedicine.

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Fluorescence Lifetime Imaging and Fourier Transform Infrared Spectroscopy of Michelangelo's David

Applied Spectroscopy ◽

10.1366/0003702055012663 ◽

2005 ◽

Vol 59 (9) ◽

pp. 1174-1181 ◽

Cited By ~ 19

Author(s):

Daniela Comelli ◽

Gianluca Valentini ◽

Rinaldo Cubeddu ◽

Lucia Toniolo

Keyword(s):

Fourier Transform ◽

Fluorescence Lifetime ◽

Imaging System ◽

Inorganic Compounds ◽

Fluorescence Emission ◽

Chemical Characterization ◽

Fourier Transform Infrared ◽

Fluorescence Lifetime Imaging ◽

Lifetime Imaging ◽

Analytical Measurements

We developed a combined procedure for the analysis of works of art based on a portable system for fluorescence imaging integrated with analytical measurements on microsamples. The method allows us to localize and identify organic and inorganic compounds present on the surface of artworks. The fluorescence apparatus measures the temporal and spectral features of the fluorescence emission, excited by ultraviolet (UV) laser pulses. The kinetic of the emission is studied through a fluorescence lifetime imaging system, while an optical multichannel analyzer measures the fluorescence spectra of selected points. The chemical characterization of the compounds present on the artistic surfaces is then performed by means of analytical measurements on microsamples collected with the assistance of the fluorescence maps. The previous concepts have been successfully applied to study the contaminants on the surface of Michelangelo's David. The fluorescence analysis combined with Fourier transform infrared (FT-IR) measurements revealed the presence of beeswax, which permeates most of the statue surface, and calcium oxalate deposits mainly arranged in vertical patterns and related to rain washing.

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A novel technique for mapping viscosity in discrete subcellular locations with a BODIPY based fluorescent probe

10.1101/522532 ◽

2019 ◽

Cited By ~ 1

Author(s):

Lior Pytowski ◽

Alex C. Foley ◽

Zayra E. Hernández ◽

Niall Moon ◽

Tim Donohoe ◽

...

Keyword(s):

Fluorescence Lifetime ◽

Fluorescence Lifetime Imaging ◽

Mitochondrial Matrix ◽

Molecular Rotor ◽

Cellular Processes ◽

Lifetime Imaging ◽

Novel Technique ◽

Absolute Viscosity ◽

Membrane Bound ◽

Fluorescent Molecules

AbstractNumerous cellular processes, including enzyme behaviour, signalling, and protein folding and transport are highly influenced by the local microviscosity environment within living cells. Molecular rotors are fluorescent molecules that respond to the viscosity of their environment through changes in both the intensity and lifetime of their fluorescence. We have synthesised a novel boron-dipyrrin (BODIPY) molecular rotor that is also a substrate for the SNAP-tag targeting system (named BG-BODIPY), allowing us to target the rotor to discrete locations within the living cell. We demonstrate that BG-BODIPY reports viscosity, and that this can be measured either through fluorescence lifetime or intensity ratiometric measurements. The relative microviscosities within the ER, Golgi, mitochondrial matrix, peroxisomes, lysosomes, cytoplasm, and nucleoplasm were significantly different. Additionally, this approach permitted fluorescence lifetime imaging microscopy (FLIM) to determine the absolute viscosity within both mitochondria and stress granules, showcasing BG-BODIPY’s usefulness in studying both membrane bound and membraneless organelles. These results highlight targeted BG-BODIPY’s broad usefulness for making measurements of cellular viscosity both with FLIM and conventional confocal microscopy, the latter option greatly extending the accessibility of the technique.

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Synthesis, Photophysics, and Solvatochromic Studies of an Aggregated-Induced-Emission Luminogen Useful in Bioimaging

Sensors ◽

10.3390/s19224932 ◽

2019 ◽

Vol 19 (22) ◽

pp. 4932 ◽

Cited By ~ 2

Author(s):

Laura Espinar-Barranco ◽

Marta Meazza ◽

Azahara Linares-Perez ◽

Ramon Rios ◽

Jose Manuel Paredes ◽

...

Keyword(s):

Fluorescence Lifetime ◽

Fluorescence Emission ◽

Fluorescence Lifetime Imaging ◽

Selective Isolation ◽

Time Resolved Fluorescence ◽

Time Resolved ◽

Lifetime Imaging ◽

Intracellular Compartments ◽

Photophysical Behavior ◽

Heterogeneous Matrix

Biological samples are a complex and heterogeneous matrix where different macromolecules with different physicochemical parameters cohabit in reduced spaces. The introduction of fluorophores into these samples, such as in the interior of cells, can produce changes in the fluorescence emission properties of these dyes, caused by the specific physicochemical properties of cells. This effect can be especially intense with solvatofluorochromic dyes, where changes in the polarity environment surrounding the dye can drastically change the fluorescence emission. In this article, we studied the photophysical behavior of a new dye and confirmed the aggregation-induced emission (AIE) phenomenon with different approaches, such as by using different solvent proportions, increasing the viscosity, forming micelles, and adding bovine serum albumin (BSA), through analysis of the absorption and steady-state and time-resolved fluorescence. Our results show the preferences of the dye for nonpolar media, exhibiting AIE under specific conditions through immobilization. Additionally, this approach offers the possibility of easily determining the critical micelle concentration (CMC). Finally, we studied the rate of spontaneous incorporation of the dye into cells by fluorescence lifetime imaging and observed the intracellular pattern produced by the AIE. Interestingly, different intracellular compartments present strong differences in fluorescence intensity and fluorescence lifetime. We used this difference to isolate different intracellular regions to selectively study these regions. Interestingly, the fluorescence lifetime shows a strong difference in different intracellular compartments, facilitating selective isolation for a detailed study of specific organelles.

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Lysosomal tracking with a cationic naphthalimide using multiphoton fluorescence lifetime imaging microscopy

Chemical Communications ◽

10.1039/c7cc05166b ◽

2017 ◽

Vol 53 (81) ◽

pp. 11161-11164 ◽

Cited By ~ 19

Author(s):

Meng Li ◽

Haobo Ge ◽

Vincenzo Mirabello ◽

Rory L. Arrowsmith ◽

Gabriele Kociok-Köhn ◽

...

Keyword(s):

Fluorescence Lifetime ◽

Fluorescence Emission ◽

Fluorescence Lifetime Imaging Microscopy ◽

Fluorescence Lifetime Imaging ◽

Lifetime Imaging

A naphthalimide-based chemosensing motif capable of turning on the fluorescence emission in solution and in vitro is reported.

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Photoswitching FRET to monitor protein–protein interactions

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1805333116 ◽

2018 ◽

Vol 116 (3) ◽

pp. 864-873 ◽

Cited By ~ 20

Author(s):

Kristin H. Rainey ◽

George H. Patterson

Keyword(s):

Fluorescence Lifetime ◽

Protein Interactions ◽

Fluorescent Protein ◽

Fluorescence Lifetime Imaging Microscopy ◽

Fluorescence Lifetime Imaging ◽

Protein Protein Interactions ◽

Lifetime Imaging ◽

Powerful Approach ◽

Fluorescent Molecules ◽

In Cells

FRET is a powerful approach to study the interactions of fluorescent molecules, and numerous methods have been developed to measure FRET in cells. Here, we present a method based on a donor molecule’s photoswitching properties, which are slower in the presence vs. the absence of an acceptor. The technique, photoswitching FRET (psFRET), is similar to an established but underutilized method called photobleaching FRET (pbFRET), with the major difference being that the molecules are switched “off” rather than photobleached. The psFRET technique has some of the FRET imaging advantages normally attributed to fluorescence lifetime imaging microscopy (FLIM), such as monitoring only donor fluorescence. However, it can be performed on a conventional widefield microscope, requires less illumination light to photoswitch off than photobleaching, and can be photoswitched “on” again to repeat the experiment. We present data testing the validity of the psFRET approach to quantify FRET in cells and demonstrate its use in imaging protein–protein interactions and fluorescent protein-based biosensors.

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Synthesis, Photophysics and Solvatochromic Studies of an Aggregated-Induced-Emission Luminogen Useful in Bioimaging

10.20944/preprints201910.0139.v1 ◽

2019 ◽

Author(s):

Laura Espinar-Barranco ◽

Marta Meazza ◽

Azahara Linares-Perez ◽

Ramon Rios ◽

Jose Manuel Paredes ◽

...

Keyword(s):

Fluorescence Lifetime ◽

Fluorescence Emission ◽

Fluorescence Lifetime Imaging ◽

Selective Isolation ◽

Time Resolved Fluorescence ◽

Time Resolved ◽

Lifetime Imaging ◽

Intracellular Compartments ◽

Photophysical Behavior ◽

Heterogeneous Matrix

Biological samples are a complex and heterogeneous matrix where different macromolecules with different physicochemical parameters cohabit in reduced spaces. The introduction of fluorophores into these samples, such as in the interior of cells, can produce changes in the fluorescence emission properties of these dyes caused by the specific physicochemical properties of cells. This effect can be especially intense with solvatofluorochromic dyes, where changes in the polarity environment surrounding the dye can drastically change the fluorescence emission. In this article, we studied the photophysical behavior of a new dye and confirmed the aggregation-induced emission (AIE) phenomenon with different approaches, such as by using different solvent proportions, increasing the viscosity, forming micelles and adding bovine serum albumin (BSA), through analysis of the absorption and steady-state and time-resolved fluorescence. Our results show the preferences of the dye for nonpolar media, exhibiting AIE under specific conditions through immobilization. Additionally, this approach offers the possibility of easily determining the critical micelle concentration (CMC). Finally, we studied the rate of spontaneous incorporation of the dye into cells by fluorescence lifetime imaging and observed the intracellular pattern produced by AIE. Interestingly, different intracellular compartments present strong differences in fluorescence intensity and fluorescence lifetime. We used this difference to isolate different intracellular regions to selectively study these regions. Interestingly, the fluorescence lifetime shows a strong difference in different intracellular compartments, facilitating selective isolation for a detailed study of specific organelles.

Download Full-text